In the Drilling and completion industries it is often desirable to affect tools or formations at a great distance from a surface located facility such as a rig. One example of an operation intended to affect a formation is a fracturing operation often referred to as fracing. In order to perform such an operation, hydraulic pressure is built within a tubing string until the pressure exceeds formation capability for holding that pressure and fractures the formation. This type of operation is most effective if done in small incremental sections of a borehole for reasons related to control and distribution of fractures to serve the ultimate purpose of the borehole. Such purposes include hydrocarbon production and Carbon Dioxide sequestration, for example.
In the art, fracturing discrete locations of the borehole tends to require a number of tools related to the pressuring of discrete locations. Where multiple fracturing locations are contemplated, generally a staged system must be built and administered correctly for it to work. One such system uses progressively larger seat diameters from the toe back to surface and then corresponding progressively increasing diameter plugs or balls. While the system works well, it is limited by the number of different size balls that can be used. Tolerance is also required in any system (due to such things as irregular shape of tubing secondary to borehole irregularity), which therefore further limits the number of diameters usable in a particular system.
Since fracturing and other operations where it is desirable to isolate discrete locations continue to become more prevalent and ubiquitous, alternate systems for accessing and manipulating the downhole environment are always well received.